Study of ARO-APOC3 in Adults With Familial Chylomicronemia Syndrome (FCS)

Inclusion Criteria:

1. Fasting TG ≥ 10 mmol/L (≥ 880 mg/dL) at screening refractory to standard lipid lowering therapy
2. Diagnosis of FCS
3. Willing to follow dietary counseling as per investigator judgement based on local standard of care
4. Participants of childbearing potential (males & females) must use highly-effective contraception during the study and for at least 24 weeks following the last dose of study medication. Males must not donate sperm during the study and for at least 24 weeks following the last dose of study medication
5. Women of childbearing potential must have a negative pregnancy test at Screening and cannot be breastfeeding
6. Women of childbearing potential on hormonal contraceptives must be stable on the medication for ≥ 2 menstrual cycles prior to Day 1

Exclusion Criteria:

1. Current use or use within the last 365 Days from Day 1 of any hepatocyte-targeted siRNA or antisense oligonucleotide molecule
2. Diabetes mellitus newly diagnosed within 12 weeks of Screening or where HbA1c ≥ 9.0% at Screening
3. Active pancreatitis within 12 weeks before Day 1
4. History of acute coronary syndrome event within 24 weeks of Day 1
5. History of major surgery within 12 weeks of Day 1
6. Uncontrolled hypertension
7. On treatment with human immunodeficiency virus (HIV) antiretroviral therapy
8. Seropositive for hepatitis B virus (HBV) or hepatitis C virus (HCV)
9. New York Heart Association (NYHA) Clas II, III, or IV heart failure

Note: Additional Inclusion/Exclusion criteria may apply per protocol